Embodiments of the invention relate to a printing sleeve for use in lithographic printing including a compressible layer and a reinforcing layer, and more particularly, to a printing sleeve including a polymeric cord reinforcing layer or a polymeric reinforcing layer which provides a smooth surface to support an outer print surface layer to provide improved print performance while enabling a reduction in the overall thickness of the reinforcing layer.
One of the most common commercial printing processes is offset lithography. In this printing process, ink is offset from a printing plate to a rubber-surfaced printing blanket or sleeve before being transferred to a substrate, such as paper. Where a printing sleeve is used, it is typically constructed using a thin metal or reinforced polymer cylindrical base or carrier, and then the layers comprising the sleeve are attached to the carrier. Such layers can include one or more compressible layers, one or more reinforcing layers, and an outer print surface layer.
The reinforcing layer for current commercial sleeves typically comprises a spun cord layer, which is comprised of materials such as polyester, nylon, polyimide, or para-aramid, such as Kevlar®. The spun cord layer stabilizes and reinforces the other functional layers on the sleeve. However, a disadvantage of such spun cord materials is that the resulting reinforcing layer does not exhibit surface uniformity, which can result in the problem of threads or textures from the underlying reinforcement layer causing non-uniformities in the printing face, and ultimately the printed image. In addition, the reinforcing layer is typically about 0.008 to 0.010 inches (0.2 mm to 0.254 mm) in thickness. In order to improve print quality, it would be desirable to provide a printing sleeve (or blanket) in which the reinforcing layer has a reduced thickness and which does not cause non-uniformities in the printing face. Such a thinner reinforcing layer would allow the use of a thicker compressible layer without increasing the overall thickness of the sleeve. This, in turn, would avoid undesirable compression set and improve print quality. Accordingly, there is a need in the art for a printing sleeve which provides improved print performance.